[dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not terminated

[Piasecki, JacekX]

-----Original Message-----
From: Maxime Coquelin [mailto:maxime.coquelin at redhat.com] 
Sent: Monday, 2 October, 2017 17:07
To: Jastrzebski, MichalX K <michalx.k.jastrzebski at intel.com>; yliu at fridaylinux.org
Cc: dev at dpdk.org; Jain, Deepak K <deepak.k.jain at intel.com>; Piasecki, JacekX <jacekx.piasecki at intel.com>; Liu, Changpeng <changpeng.liu at intel.com>; stable at dpdk.org
Subject: Re: [dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not terminated



On 10/02/2017 03:50 PM, Jastrzebski, MichalX K wrote:
>> -----Original Message-----
>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Michal 
>> Jastrzebski
>> Sent: Friday, September 22, 2017 3:08 PM
>> To: yliu at fridaylinux.org; maxime.coquelin at redhat.com
>> Cc: dev at dpdk.org; Jain, Deepak K <deepak.k.jain at intel.com>; Piasecki, 
>> JacekX <jacekx.piasecki at intel.com>; Liu, Changpeng 
>> <changpeng.liu at intel.com>; stable at dpdk.org
>> Subject: [dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not 
>> terminated
>>
>> From: Jacek Piasecki <jacekx.piasecki at intel.com>
>>
>> Fix size of buffer in strcpy. There was possible to get not 
>> terminated string after copy operation.
>>
>> Coverity issue: 158631
>> Fixes: db75c7af19bb ("examples/vhost_scsi: introduce a new sample 
>> app")
>> Cc: changpeng.liu at intel.com
>> Cc: stable at dpdk.org
>>
>> Signed-off-by: Jacek Piasecki <jacekx.piasecki at intel.com>
>> ---
>>   examples/vhost_scsi/scsi.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/examples/vhost_scsi/scsi.c b/examples/vhost_scsi/scsi.c 
>> index 54d3104..de9639a 100644
>> --- a/examples/vhost_scsi/scsi.c
>> +++ b/examples/vhost_scsi/scsi.c
>> @@ -307,7 +307,8 @@
>>   		strncpy((char *)inqdata->t10_vendor_id, "INTEL", 8);
>>
>>   		/* PRODUCT IDENTIFICATION */
>> -		strncpy((char *)inqdata->product_id, bdev->product_name,
>> 16);
>> +		strncpy((char *)inqdata->product_id, bdev->product_name,
>> +				ARRAY_SIZE(inqdata->product_id) - 1);

Does it assume that product_id is memzero'ed before?
IIUC strncpy manpage, it wouldn't protect against non-null terminated strings if it is not the case:

Yes, I assumed that this area is zeroed before strncpy. Earlier there is a casting from *task to *inqdata (*task is zmalloced).
To be sure that the destination area is clear I propose to add:
memset(inqdata->product_id, 0, ARRAY_SIZE(inqdata->product_id));
before strncpy. Would that be OK?

Regards,
Jacek

>>
>>   		/* PRODUCT REVISION LEVEL */
>>   		strncpy((char *)inqdata->product_rev, "0001", 4);
>> --
>> 1.9.1
> 
> Hi Yu / Maxime,
> I would like to ask for a feedback regarding proposed fix.
> If everything is ok with it, please send acked-by.
> 
> Best regards
> Michal.
>